Containment heatsink for packaged battery cells

ABSTRACT

An apparatus for cooling and containing packaged battery cells includes a first structure disposed on a printed circuit board for encasing a first battery cell, the first battery cell being electrically coupled to the circuit board, the first structure includes an external surface and an internal surface defining a first cavity in which the first battery cell is located. The apparatus further includes a first seal surrounding the first battery cell between the printed circuit board coupled to the first structure. The apparatus further includes a first thermal interface material located in the first cavity, wherein a first portion of the first thermal interface material is thermally coupled to an interior surface and a second portion of the first thermal interface material is thermally coupled to the first battery cell. The apparatus further includes a plurality of heatsink fins located on the external surface of the first structure.

FIELD OF THE INVENTION

This disclosure relates generally to packaging battery cells, and inparticular, to structures for cooling and containing individuallypackaged battery cells.

BACKGROUND OF THE INVENTION

Over time, energy density in batteries has increased, while packagingsize for the batteries has decreased. Lithium ion batteries are anexample of high energy density batteries and have become the preferredbattery technology for items such as consumer electronics, electricvehicles, battery backup systems, and systems requiring a mobile andrechargeable power source. A byproduct of high energy density is thatlithium ion batteries pose a greater safety risk than lower energydensity technologies due to the amount of chemical energy stored in asmall package. A mechanism by which high energy density batteries failenergetically is called thermal runaway, a condition where the chemicalreaction inside a single cell becomes unstable due to excessive heat,which may be generated by an internal defect or by other means. Thermalrunaway causes the single cell to continue to heat up at anever-accelerating rate until the structural integrity of the single cellis compromised or the single cell combusts.

SUMMARY

One embodiment of the present invention discloses an apparatus forcontaining packaged battery cells, the apparatus comprising a firststructure disposed on a printed circuit board for encasing a firstbattery cell, the first battery cell being electrically coupled to thecircuit board, the first structure includes an external surface and aninternal surface defining a first cavity in which the first battery cellis located. The apparatus includes the first cavity located on a bottomsurface of the first structure, wherein the bottom surface of the firststructure is coupled to a top surface of the printed circuit board. Theapparatus further includes a first seal surrounding an area of the firstbattery cell between the top surface of the printed circuit boardcoupled to the bottom surface of the first structure. The apparatusfurther includes a first thermal interface material located in the firstcavity, wherein a first portion of the first thermal interface materialis thermally coupled to an interior surface of the first cavity and asecond portion of the first thermal interface material is thermallycoupled to at least a portion of the first battery cell located in thefirst cavity. The apparatus further includes a plurality of heatsinkfins located on the external surface of the first structure.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description, given by way of example and notintended to limit the disclosure solely thereto, will best beappreciated in conjunction with the accompanying drawings, in which:

FIG. 1 depicts a battery cell board assembly with a blast plate andcontainment heatsink, in accordance with an embodiment of the presentinvention.

FIG. 2 depicts a transparent view of a containment heatsink from FIG. 1,in accordance with an embodiment of the present invention.

FIG. 3 depicts an enhanced view of a battery cell board assembly with ablast plate and containment heatsink, in accordance with one embodimentof the present invention.

FIG. 4 depicts an individual battery cell located within a singlecompartment of a containment heatsink, in accordance with one embodimentof the present invention.

FIG. 5 depicts a transparent bottom view of paired battery cells incompartments of a containment heatsink, in accordance with oneembodiment of the present invention.

FIG. 6 depicts a transparent top view of paired battery cells in asingle compartment of a containment heatsink, in accordance with oneembodiment of the present invention.

FIG. 7 depicts a transparent bottom view of paired battery cells in asingle compartment of a containment heatsink, in accordance with oneembodiment of the present invention.

DETAILED DESCRIPTION

Larger battery cell packages containing multiple battery cells aretypically cooled utilizing liquid coolant, where the coolant flowsthrough tubing and piping around the battery cells to cool the batterycell package. The coolant draws heat away from the battery cells andallows for a containment unit to be placed around the cells to prevent athermal runaway event from escaping the confines of the battery cellpackage. Some larger battery cell packages separate the battery cellsinto smaller clusters or modules which are isolated, preventing acascading failure of all the battery cells in the battery cell package.It is atypical to provide cooling to larger battery cell packagesutilizing air flow due to the difficulty of containing battery cells.The containment of battery cells prevents an uncontrolled event (e.g.,fire) from exiting the battery cell package and causing damage orinjury. The containment of a single battery cell prevents a singlebattery cell thermal runaway event from propagating to surroundingbattery cells and creating a thermal runaway event across all thebattery cells within the battery cell package.

Embodiments of the present invention provide an apparatus for coolingand containing an array of battery cells in a battery cell package,while utilizing accelerated airflow as a primary cooling method. Acontainment heatsink with multiple compartments is utilized to isolateand provide cooling to individual or paired battery cells located withineach compartment, where the array of battery cells are electricallycoupled to a printed circuit board. A top surface of the containmentheatsink includes fins for dissipating heat produced by the array ofbattery cells and a bottom surface includes multiple cavities forisolating individual or paired battery cells. The containment heatsinkis coupled to a top surface of the printed circuit board with theelectrically coupled array of battery cells, where the individual orpaired battery cells are encased between the containment heatsink andthe printed circuit board. The individual or paired battery cells arepartially encased (e.g., five sides) in the cavity of the containmentheatsink, where the printed circuit board provides a boundary (i.e.,sixth side) for completely encasing the individual or paired batterycells. Each battery cell or cluster of battery cells, isolated in acompartment of the containment heatsink prevents the propagation of athermal event to the surrounding array of battery cells (thermalrunaway).

A blast plate structure can be utilized in combination with thecontainment heatsink to provide containment during the thermal event,where the blast structures couples to a bottom surface of the printedcircuit board. The blast structure can be of a metal or ceramic materialcapable of withstanding a force and heat generated during the thermalevent occurring in one or more compartments of the containment heatsinkthat has penetrated the bottom surface of the printed circuit board. Avoid exists between a top surface of the blast plate structure and abottom surface of the printed circuit board to allow for the electricalcoupling of battery management circuitry such as integrated circuits(ICs), resistors, and field-effect transistors (FETs). Apertures can beincorporated in the printed circuit board for releasing pressuregenerated by a battery cell experiencing a thermal event in acompartment. The void allows for the pressure generated by the batteryto dissipate, prior to the pressurized gas encountering the blast platestructure situated opposite the apertures in the printed circuit board.

The individual or paired battery cells are thermally coupled via athermal interface material to an inside surface of the compartment. Thethermal interface material can be thermally coupled on any insidesurface of the compartment depending on the application. For example, ifthe containment heatsink is of an electrically conductive material, thethermal interface material is thermally coupled to all inside surfacesof the compartment to prevent the battery leads of the battery cellsfrom contacting the conductive containment heatsink. Heat is transferredfrom the battery cells to the thermal interface material and from thethermal interface material to the containment heatsink. As one or morefans accelerate air towards the containment heatsink, the acceleratedair contacts heatsink fins located on a top surface of the containmentheatsink and cools the containment heatsink with the array of batterycells encased within. Since the array of battery cells are thermallycoupled to the containment heatsink via the thermal interface material,heat can transfer from the battery cell to the heatsink fins. The arrayof battery cells encased by the containment heatsink are simultaneouslycontained and cooled utilizing the accelerated air cooling method.

Detailed embodiments of the present invention are disclosed herein withreference to the accompanying drawings; however, it is to be understoodthat the disclosed embodiments are merely illustrative of potentialembodiments of the invention and may take various forms. In addition,each of the examples given in connection with the various embodiments isalso intended to be illustrative, and not restrictive. This descriptionis intended to be interpreted merely as a representative basis forteaching one skilled in the art to variously employ the various aspectsof the present disclosure. In the description, details of well-knownfeatures and techniques may be omitted to avoid unnecessarily obscuringthe presented embodiments.

For purposes of the description hereinafter, terms such as “upper”,“lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, andderivatives thereof shall relate to the disclosed structures andmethods, as oriented in the drawing figures. Terms such as “above”,“overlying”, “atop”, “on top”, “positioned on” or “positioned atop” meanthat a first element, such as a first structure, is present on a secondelement, such as a second structure, wherein intervening elements, suchas an interface structure may be present between the first element andthe second element. The term “direct contact” means that a firstelement, such as a first structure, and a second element, such as asecond structure, are connected without any intermediary conducting,insulating or semiconductor layers at the interface of the two elements.The term substantially, or substantially similar, refer to instances inwhich the difference in length, height, or orientation convey nopractical difference between the definite recitation (e.g. the phrasesans the substantially similar term), and the substantially similarvariations. In one embodiment, substantial (and its derivatives) denotea difference by a generally accepted engineering or manufacturingtolerance for similar devices, up to, for example, 10% deviation invalue or 10° deviation in angle.

In the interest of not obscuring the presentation of embodiments of thepresent invention, in the following detailed description, someprocessing steps or operations that are known in the art may have beencombined together for presentation and for illustration purposes and insome instances may have not been described in detail. In otherinstances, some processing steps or operations that are known in the artmay not be described at all. It should be understood that the followingdescription is rather focused on the distinctive features or elements ofvarious embodiments of the present invention.

Many common fabrication techniques involve securing two objects using anadhesive layer between the objects. Often times the adhesive layer ischosen in an attempt to permanently secure the two objects together. Andwhile this adhesive layer selection may be advantageous for typicalusage of the overall product, there may be instances where separation ofthe joined objects is either desired, or necessary. In such instances,separation of the two objects, without physically damaging either of theobjects, may be required so that one or both of the objects may bereused.

FIG. 1 depicts a battery cell board assembly with a blast plate andcontainment heatsink, in accordance with an embodiment of the presentinvention. In this embodiment, battery cell board assembly 100 includescontainment heatsink 102, heatsink fins 104, and printed circuit board(PCB) 106. Battery cell board assembly 100 includes an array of batterycells spanning the length of PCB 106, where each battery cell is mountedlongitudinally relative to a top surface of PCB 106. Each battery cellis encased in a battery cell compartment, discussed in further detail inFIG. 2. A bottom surface of a first end of each battery cell and a topsurface of a second end of each battery cell is electrically coupled toa top surface of PCB 106. Sealing each battery cell prevents a thermalevent occurring in a single battery cell from propagating to surroundingbattery cells (i.e., thermal runaway). In this embodiment, containmentheatsink 102 and heatsink fins 104 are a single mountable structurecoupled to PCB 106, where the singled mountable structure is placed overthe array of battery cells and battery cell components spanning thelength of PCB 106 and the single mountable structure couples to a topsurface of PCB 106. In an alternative embodiment, containment heatsink102 and heatsink fins 104 are each distinguishable structures, wherecontainment heatsink 102 and heatsink fins 104 can be assembled prior tocoupling to a top surface of PCB 106 or containment heat sink 102 cancouple to a top surface of PCB 106 and heatsink fins 104 can couple to atop surface of containment heatsink 102.

A bottom surface of containment heatsink 102 couples to a top surface ofPCB 106, where a seal is created around a perimeter of containmentheatsink and a seal is created around each battery cell compartmentencasing one or more battery cells. A shape and size of containmentheatsink 102 is dependent on a number of battery cells coupled to PCB106. A shape and size of heatsink fins 104 is dependent on coolingrequirements for the battery cells coupled to PCB 106. In thisembodiment, rows of heatsink fins 104 are orientated longitudinally,where the rows of heatsink fins 104 are parallel to a directionalairflow created by fans 108 located at a first end (front portion) ofbattery cell board assembly 100. Spacing between the rows of heatsinkfins 104 can vary along the length of containment heatsink 104, where aspacing between the rows of heatsink fins 104 is narrower at a first end(front portion) of containment heatsink 102 than a spacing between therows of heatsink fins 104 at a second end (rear portion) of containmentheatsink 102. A height for each row of heatsink fins 104 can vary alongthe length of containment heatsink 104, where a height of heatsink fins104 is shorter at the first end of containment heatsink 102 than aheight of heatsink fins 104 at the second end of containment heat sink102. Variations of height and spacing between rows of heatsink fins 104addresses increased cooling requirements along the length of containmentheatsink 102, towards the second end of containment heatsink 102.

Blast plate structure 110 is coupled to a bottom surface of the PCB 106,where a void is present between the bottom surface of PCB 106 and blastplate structure 110. The void allows for the placement of electricalcomponents on the bottom surface of PCB 106 and the void allows forpressure relief for the battery cells through apertures in PCB 106. Eachbattery cell compartment includes one or more dedicated apertures in PCB106 to allow for gas to flow out through the battery cell during ahigh-pressure event, through the one or more apertures in PCB 106, andout into the void between PCB 106 and blast plate structure 110. Inanother embodiment, each battery cell compartment includes one or morededicated apertures in containment heatsink 102 to allow for gas to flowout through the battery cell during a high-pressure event, through theone or more apertures in containment heatsink 102, and away from thesurrounding battery cell compartments.

For illustration purposes, FIG. 1 does not include an enclosure forbattery cell board assembly 100, where the enclosure encompasses batterycell board assembly 100. Cooling fans 108 located at the first end(front portion) of battery cell board assembly 100 accelerates airtowards containment heat sink 102 with heatsink fins 104, and exhaustsair away from containment heat sink 102 with heatsink fins 104 at asecond end (rear portion) of battery cell board assembly 100. Theenclosure at the first end of battery cell board assembly 100 includesinlet apertures for air intake and the enclosure at the second end ofbattery cell board assembly 100 includes outlet apertures for exhaustingair away from battery cell board assembly 100.

FIG. 2 depicts a transparent view of a containment heatsink from FIG. 1,in accordance with an embodiment of the present invention. Forillustration purposes, containment heatsink 102 is shown as transparentfor visualization of content encased within. In this embodiment, eachbattery cell compartment 202 positioned along the length of transparentbattery cell board assembly 200, includes a pair of battery cells 204.The two battery cell compartments 202 positioned at the first end andthe second end of containment heatsink 102, are positioned along thewidth of transparent battery cell board assembly 200 and each of the twobattery compartments include a single battery cell 204. An orientationof battery cells 204 and a number of battery cells 204 in a singlebattery cell compartment 202 is dependent on cooling, containment, andpackaging requirements of a specific application.

FIG. 3 depicts an enhanced view of a battery cell board assembly with ablast plate and containment heatsink, in accordance with one embodimentof the present invention. Enhanced view of containment heat sink 300illustrates containment heatsink 102 with heatsink fins 104 coupled toPCB 106. As previously discussed, blast plate structure 110 is coupledto a bottom surface of the PCB 106, where void 302 is present betweenthe bottom surface of PCB 106 and blast plate structure 110. Void 302allows for the placement of electrical components on the bottom surfaceof PCB 106 and void 302 allows for pressure relief for the battery cellsthrough one or more apertures in PCB 106. Blast plate structure 110 incombination with PCB 106, provides protection on a bottom surface of thecontainment heatsink 102 with battery cell compartments that encase thebattery cells electrically coupled to PCB 106.

A top surface of blast plate structure 110 can couple to a bottomsurface PCB 106 utilizing multiple member structures, where each of themultiple member structures are perpendicular to the top surface of blastplate structure 110 and bottom surface of PCB 106. In one embodiment,the multiple member structures for mounting blast plate structure 110can be incorporated into a mold of blast plate structure 110, resultingin a single blast plate structure 110 with protruding member structures.In another embodiment, the multiple member structures for mounting blastplate structure can be incorporated into PCB 106, resulting in a singlePCB 106 structure with protruding members for mounting blast platestructure 110. In yet another embodiment, containment heatsink 102includes the multiple member structures which pass through a top surfaceof PCB 106 and exit a bottom surface of PCB 106, where each end of themultiple member structures couple to blast plate structure 110.

FIG. 4 depicts an individual battery cell located within a singlecompartment of a containment heatsink, in accordance with one embodimentof the present invention. Enhanced battery compartment view 400illustrates a side view of battery cell 204 encased by containmentheatsink 102 and PCB 106. Battery cell 204 is electrically coupledlengthwise to PCB 106 through electrical leads at a first end and asecond end of battery cell 204. Thermal interface material 402 ispositioned between a first portion of battery cell 204 and containmentheatsink 102, where the first portion of battery cell 204 is positionedopposite of a top surface of a battery cell compartment. Alternatively,thermal interface material 402 can be positioned between all surfaces ofbattery cell 402 opposite the battery cell compartment of containmentheatsink 102. Thermal interface material 402 prevents electricalconduction between battery cell 204 and containment heatsink 102 andthermal interface material 402 provides a thermal path for heat to flowfrom battery cell 204 to containment heatsink 102 and from containmentheatsink 102 to heatsink fins 104 (not illustrated in FIG. 4).Containment heatsink 102 can couple to PCB 106 utilizing a heatresistant adhesive, such that the heat resistant adhesive creates a sealsurrounding battery cell 204 preventing gasses from escaping betweencontainment heatsink 102 and PCB 106. Alternatively, containmentheatsink 102 can couple to PCB 106 with multiple fasteners (e.g.,screws) and heat resistant gaskets, such that the heat resistant gasketcreates a seal surrounding battery cell 204 preventing gasses fromescaping between containment heatsink 102 and PCB 106.

FIG. 5 depicts a transparent bottom view of paired battery cells incompartments of a containment heatsink, in accordance with oneembodiment of the present invention. Transparent printed circuit boardview 500 illustrates a bottom view of PCB 106 with battery cellcompartments 202 encasing battery cells 204. In this embodiment, eachbattery cell compartment 202 includes a pair of battery cells 204, wherevoids 502 exist between each battery cell compartment 202 to isolateeach paring of battery cells 204. In the embodiment where containmentheatsink 102 is coupled to PCB 106 utilizing fasteners, one or more heatresistant gaskets would be situated in voids 502 between containmentheatsink 102 and PCB 106. In the embodiment where containment heatsink102 is coupled to PCB 106 utilizing a heat resistant adhesive, the heatresistant adhesive would be situated in voids 502.

FIG. 6 depicts a transparent top view of paired battery cells in asingle compartment of a containment heatsink, in accordance with oneembodiment of the present invention. Transparent battery cellcompartment 600 illustrates a top view of battery cell compartment 202encasing paired battery cells 204. In this embodiment, the pairedbattery cells 204 are mounted lengthwise on PCB 106, with thermalinterface material 402 situated on a top surface of the paired batterycells 204. Battery cell compartment 202 includes multiple apertures inPCB 106 for venting gasses produced by the paired battery cells 204during a thermal event, where the multiple apertures in PCB 106 arediscussed in further detail with regards to FIG. 7. In an alternativeembodiment, multiple apertures are located on containment heatsink 102for battery cell compartment 202, where the multiple apertures arelocated in between heatsink fins 104 of containment heatsink 102.

FIG. 7 depicts a transparent bottom view of paired battery cells in asingle compartment of a containment heatsink, in accordance with oneembodiment of the present invention. Transparent printed circuit board700 illustrates PCB 106 with apertures 702 for venting gases produced bypaired battery cells 204 in battery cell compartment 202. In thisembodiment, battery cell compartment 202 includes apertures 702 in PCB106 for venting gasses produced by the paired battery cells 204 during athermal event. Battery cell compartment 202 of containment heat sink 102prevents gasses produced by the paired battery cells 204 frompropagating to surrounding battery cells 204 encased in respectivebattery cell compartments 202. A size and location of apertures 702 isdependent on an amount of pressure generated in battery cell compartment202 when the paired battery cells 204 experience a thermal event.Apertures 702 are sized such that gasses produced by the paired batterycells 204 experiencing a thermal event, is gradually released withoutdamaging portions of PCB 106 located beneath surrounding paired batterycells 204. The gradual release of gasses from the battery cellcompartment prevents the thermal event from propagating to thesurrounding paired battery cells 204, thus preventing a thermal runawayevent.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting to the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiment, the practical application or technicalimprovement over technologies found in the marketplace, or to enableother of ordinary skill in the art to understand the embodimentsdisclosed herein. It is therefore intended that the present inventionnot be limited to the exact forms and details described and illustratedbut fall within the scope of the appended claims.

What is claimed is:
 1. An apparatus for cooling and containing packagedbattery cells, the apparatus comprising: a first structure disposed on aprinted circuit board, the first structure and the printed circuit boardencase a first battery cell, the first battery cell being electricallycoupled to the printed circuit board, the first structure including anexternal surface and an internal surface defining a first compartment inwhich the first battery cell is located; the first compartment locatedon a bottom surface of the first structure, wherein the bottom surfaceof the first structure is coupled to a top surface of the printedcircuit board; a first seal surrounding an area of the first batterycell between the top surface of the printed circuit board coupled to thebottom surface of the first structure; a first thermal interfacematerial located in the first compartment, wherein a first portion ofthe first thermal interface material is thermally coupled to an interiorsurface of the first compartment and a second portion of the firstthermal interface material is thermally coupled to at least a portion ofthe first battery cell located in the first compartment; one or moreapertures on the printed circuit board, wherein the one or moreapertures are located within an area of the first compartment configuredto provide pressure relief for the first compartment in which the firstbattery cell is located; a first blast plate structure coupled to thebottom surface of the first structure, wherein the bottom surface of thefirst structure includes one or more protruding members extendingthrough the printed circuit board, for coupling the first blast platestructure, wherein a first void separates a bottom surface of theprinted circuit board and a top surface of the first blast platestructure; and a plurality of heatsink fins located on the externalsurface of the first structure.
 2. The apparatus of claim 1, wherein thefirst seal is a heat resistant gasket coupled between the printedcircuit board and the surrounding surface of the first compartment. 3.The apparatus of claim 1, wherein the first seal is a heat resistantadhesive disposed between the printed circuit board and the surroundingsurface of the first compartment.
 4. The apparatus of claim 2, whereinthe printed circuit board is coupled to the first structure via one ormore fasteners extending through the heat resistant gasket.
 5. Theapparatus of claim 3, wherein the printed circuit board is coupled tothe first structure via one or more fasteners extending through the heatresistant adhesive.
 6. The apparatus of claim 1, further comprising: oneor more apertures located on the top surface of the first structurebetween the plurality of heatsink fins, wherein the one or moreapertures are located within an area of first compartment.
 7. Theapparatus of claim 1, further comprising: a second blast plate structurecoupled to the bottom surface of the printed circuit board, wherein thebottom surface of the printed circuit board includes one or moreprotruding members for coupling to the second blast plate structure. 8.The apparatus of claim 1, wherein the first blast plate structurecomprises a ceramic material.
 9. The apparatus of claim 7, wherein thesecond blast plate structure comprises a ceramic material.
 10. Theapparatus of claim 1, further comprising: a second compartment locatedon the bottom surface of the first structure for partially encasing asecond battery cell electrically coupled to the printed circuit board;and a second thermal interface material situated in the secondcompartment, wherein a first portion of the second thermal interfacematerial is thermally coupled to an interior surface of the secondcompartment and a second portion of the second thermal interfacematerial is thermally coupled to at least a portion of the secondbattery cell located in the second compartment; wherein the printedcircuit board is coupled to the first structure.
 11. The apparatus ofclaim 10, wherein a first void in the first structure separates thefirst compartment and the second compartment.
 12. The apparatus of claim10, wherein a first portion of the plurality of heatsink fins arelocated above the first compartment and a second portion of theplurality of heatsink fins are located above the second compartment. 13.The apparatus of claim 1, wherein the first battery cell electricallycoupled to the printed circuit board is longitudinally oriented relativeto the top surface of the printed circuit board.